Access port and catheter assembly including catheter distal portion stability features

ABSTRACT

A catheter for insertion into a body of a patient, and methods of making and using. The catheter can include a distal portion that remains stable during fluid infusion into the patient, thus reducing or eliminating whipping of the catheter distal tip. The catheter includes at least one lumen and can be configured such that the arithmetic product of an elastic modulus and an area moment of inertia for the distal portion of the catheter is greater than the arithmetic product of an elastic modulus and an area moment of inertia for a proximal portion. The catheter can be attached to an implantable access port that may include features for use as a power injectable access port.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/002,335, filed Jan. 20, 2016, now U.S. Pat. No. 10,238,833, which isa continuation-in-part of U.S. patent application Ser. No. 13/209,270,filed Aug. 12, 2011, and titled “Trimmable Catheter Including DistalPortion Stability Features,” now U.S. Pat. No. 9,913,960, which claimsthe benefit of U.S. Provisional Patent Application No. 61/373,000, filedAug. 12, 2010, and titled “Trimmable Catheter Including a Flared DistalPortion,” which is incorporated herein by reference in its entirety.

BRIEF SUMMARY

Briefly summarized, embodiments of the present invention are directed toa catheter assembly used to gain access to a vasculature or otherinternal portion of a patient. The catheter assembly includes a cathetertube that defines one or more lumens, with at least one lumen optionallycapable of power injection, in one embodiment. A proximal portion of thecatheter tube is sized and configured so as to reside within a portionof the vessel that is disposed relatively close to the insertion site ofthe catheter tube into the patient. In particular, as such portions ofthe vessel are of relatively small diameter, the proximal portion of thecatheter tube is similarly of relatively small diameter and ofrelatively low stiffness so as to prevent substantial occlusion of thevessel by the catheter tube and lessen vessel damage.

Moreover, a distal portion of the catheter tube is sized and configuredsuch that the distal portion remains stable within the vessel duringinfusion of fluids therethrough. Particularly, the distal portion of thecatheter tube is configured to avoid whipping of the distal tip withinthe vessel during fluid infusion so as to prevent vessel damage. Thisstability of the catheter tube's distal portion is especially helpfulduring power injection of fluids into the vessel.

In one embodiment, stability of the distal tip of the catheter tube isaccomplished by flaring, or increasing the cross sectional size of thedistal portion of the tube, thus increasing the areal size of the one ormore catheter lumens and improving the area moment of inertia of thedistal portion. In another embodiment, the elastic modulus, orstiffness, of the distal portion can be increased relative to theproximal portion of the catheter tube. In another embodiment, both thearea moment of inertia and the modulus can be modified to enhance distalportion stability. Note that these and related parameters can bemodified in other ways as well.

Thus, in one embodiment, a catheter tube for insertion into a body of apatient is disclosed. The catheter tube includes a distal portion thatremains stable during fluid infusion into the patient, thus reducing oreliminating whipping of the catheter distal tip, even during powerinjection. In one embodiment, the catheter tube defines at least onelumen and is formed from a tube material that defines a proximal portionand a distal portion of the catheter tube. The catheter tube isconfigured such that the arithmetic product of an elastic modulus and anarea moment of inertia for at least a portion of the distal portion ofthe catheter tube defined by the catheter tube material is greaterrelative the arithmetic product of an elastic modulus and an area momentof inertia for at least a portion of the proximal portion of thecatheter tube.

In another embodiment, an implantable vascular access port system isdisclosed, wherein a stabilized catheter tube similar to that describedabove is operably connected to an implantable access port, such as anarm port, for instance. These and other uses of the stabilized cathetertube, such as its use as a PICC or other catheter assembly for providingexternal access to a patient's vasculature, are contemplated.

These and other features of embodiments of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of embodiments of theinvention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the present disclosure will be renderedby reference to specific embodiments thereof that are illustrated in theappended drawings. It is appreciated that these drawings depict onlytypical embodiments of the invention and are therefore not to beconsidered limiting of its scope. Example embodiments of the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a perspective view of a catheter assembly configured inaccordance with one embodiment;

FIG. 2 is a side view of the catheter tube of the assembly shown in FIG.1;

FIGS. 3A-3C are cross sectional views of the catheter tube of FIG. 2,showing a relative change in catheter tube structure;

FIG. 4 is a side view of a catheter tube configured in accordance withone embodiment;

FIG. 5 is a side view of a catheter tube configured in accordance withone embodiment;

FIG. 6 is a side view of a catheter tube configured in accordance withone embodiment;

FIG. 7 is a cross sectional view of a distal portion of a catheter tubein accordance with one embodiment;

FIG. 8 is a side view of a catheter tube in accordance with oneembodiment;

FIG. 9 is a side view of a catheter tube in accordance with oneembodiment;

FIG. 10 is a side view of a catheter tube in accordance with oneembodiment;

FIGS. 11A and 11B are cross sectional views of the catheter tube of FIG.10;

FIG. 12 is a cross sectional side view of a distal portion of a cathetertube in accordance with one embodiment;

FIG. 13 is a perspective view of a distal portion of a catheter tube inaccordance with one embodiment;

FIGS. 14A and 14B are cross sectional side views of a catheter tube inaccordance with one embodiment;

FIG. 15 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 16 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 17 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 18 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 19 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 20 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 21 is a cross sectional side view of a catheter tube in accordancewith one embodiment;

FIG. 22 is a side view of a catheter tube in accordance with oneembodiment;

FIGS. 23A-23C are cross sectional views of the catheter tube of FIG. 22;

FIG. 24 is a side view of a catheter tube in accordance with oneembodiment;

FIG. 25 is a distal end view of the catheter tube of FIG. 24;

FIG. 26 is a distal end view of the catheter tube of FIG. 24 in a firstrolled-up configuration;

FIG. 27 is a distal end view of the catheter tube of FIG. 24 in a secondrolled-up configuration;

FIGS. 28A and 28B are perspective and end views, respectively, of acatheter tube in accordance with one embodiment;

FIG. 29 is a side view of a vascular access port system according to oneembodiment;

FIG. 30 is a simplified cutaway view of a patient with the vascularaccess port system of FIG. 29 disposed therein, according to oneembodiment; and

FIGS. 31A-31C are cross sectional views of the catheter tube of FIG. 29,showing a relative change in catheter tube structure.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made to figures wherein like structures will beprovided with like reference designations. It is understood that thedrawings are diagrammatic and schematic representations of exemplaryembodiments of the present invention, and are neither limiting nornecessarily drawn to scale.

For clarity it is to be understood that the word “proximal” refers to adirection relatively closer to a clinician using the device to bedescribed herein, while the word “distal” refers to a directionrelatively further from the clinician. For example, the end of acatheter placed within the body of a patient is considered a distal endof the catheter, while the catheter end remaining outside the body is aproximal end of the catheter. Also, the words “including,” “has,” and“having,” as used herein, including the claims, shall have the samemeaning as the word “comprising.”

Embodiments of the present invention are generally directed to acatheter assembly used to gain access to a vasculature or other internalportion of a patient. The catheter assembly includes a catheter tubethat defines one or more lumens, with at least one lumen capable ofpower injection, in one embodiment. A proximal portion of the cathetertube is sized and configured so as to reside within a portion of thevessel that is disposed relatively close to the insertion site of thecatheter tube into the patient. In particular, as such portions of thevessel are of relatively small diameter, the proximal portion of thecatheter tube is similarly of relatively small diameter and ofrelatively low stiffness so as to enable ease of passage of the cathetertube through the vessel and to prevent substantial occlusion of thevessel by the catheter tube

Moreover, a distal portion of the catheter tube is sized and configuredsuch that it remains stable within the vessel during infusion of fluidstherethrough. Particularly, the distal portion of the catheter tube isconfigured to avoid whipping of the distal tip within the vessel duringfluid infusion so as to prevent vessel damage. This stability of thecatheter tube's distal portion is especially helpful during powerinjection of fluids into the vessel.

In one embodiment, stability of the distal tip of the catheter tube isaccomplished by flaring, or increasing the cross sectional size of thedistal portion of the tube thus increasing the areal size of the one ormore catheter lumens and improving the moment area of inertia of thedistal portion. In another embodiment, the elastic modulus, orstiffness, of the distal portion can be increased relative to theproximal portion of the catheter tube. In another embodiment, both themoment area of inertia and the modulus can be modified to enhance distalportion stability. Note that these and related parameters can bemodified in other ways as well and that additional configurations forincreasing distal tip stability are disclosed. In addition to thecatheter tubes described herein as part of catheter assemblies, theprinciples to be disclosed can be employed with other tubular medicaldevices as well.

Reference is first made to FIG. 1, which depicts various details of acatheter assembly, generally designated at 10, according to oneembodiment. As shown, the catheter assembly (“catheter”) 10 includes anelongate catheter tube 12 formed by an outer wall 13 which, togetherwith a septum 15 (FIGS. 3A-3C) defines one or more lumens 14 extendingbetween a proximal end 12A and a distal end 12B of the tube. Abifurcation 16 mates with the catheter tube 12 at the proximal end 12Athereof to provide fluid communication between the catheter tube and oneor more extension legs 18.

FIG. 2 shows further details of the catheter tube of the catheter 10,according to the present embodiment. As shown, the tube 12 includes aproximal portion 20 extending distally from the proximal end 12A and adistal portion 30 extending distally from the distal end of the proximalportion to the distal end 12B of the tube. A tapered region 24 of theproximal portion 20 is included in the catheter tube 12 and isconfigured such that the thickness of the outer wall 13 and septum 15decrease from the tube proximal end 12A to the distal termination of thetapered region 24. In addition, the areal size of each of the lumens 14also decreases distally over this region. These size differences can beseen by comparing FIGS. 3A and 3B, which show cross sectional views ofthe catheter tube 12 at the proximal end of the tapered region 24 (FIG.3A) and distal to the distal termination of the tapered region (FIG.3B).

The proximal tapered region 24 provides sufficient outer wall thicknessand rigidity for the catheter tube 12 of the present embodiment so as toprevent kinking and to enable the tube to be adjusted with respect to aninsertion site in the skin of the patient during insertion andadjustment of the catheter 10. Furthermore, the proximal tapered region24 serves to plug the insertion site through which the catheter tubepasses into the patient's body, thus reducing bleeding or othercomplications at the site.

The remainder of the proximal portion 20 of the catheter tube 12 resideswithin distal portions of the vessel that are typically locatedrelatively close to the catheter insertion site in extremities of thepatient, such as the arm. Such outlying, or distal, vessels arerelatively smaller than the larger vessels located deeper within thebody in which the distal portion 30 of the catheter tube 12 is disposed.Thus, the proximal portion 20 of the catheter tube 12 distal to thetapered region 24 is similarly sized relatively small so that thisportion can reside in the relatively small vessel without occluding asignificant portion thereof, which in turn reduces the risk of thrombus.Further, the smaller size of the proximal portion 20 enables it to bendmore easily during insertion into the vessel along a potentiallytortuous path, resulting in less trauma and damage to the vessel.

As best seen in FIG. 2, the distal portion 30 of the catheter tube 12includes a distal taper region 34 that provides a size transition forthe tube from the distal end of the proximal portion 20 and theremainder of the distal portion 30. Specifically, the distal taperregion 34 enables the dimensions of the catheter tube 12 to change fromthe cross sectional configuration corresponding to the proximal portion20 shown in FIG. 3B to that of the distal portion 30 shown in FIG. 3C,wherein the thickness of the outer wall 13 and septum 15, together withthe areal size of the lumens 14, increase. This general size increase ofthe catheter tube distal portion 30 provides enhanced stability for thisportion of the catheter tube 12, which in turn prevents oscillatorymovement, or whipping, of the distal tip of the tube during fluidinfusion through the catheter into the vessel in which the catheter 10is disposed. This in turn reduces the chance for vessel wall damagecaused by repetitive impacts of the whipping catheter tube.

In greater detail, it is appreciated that an unsupported stable length,L, of a distal portion of a catheter tube can be characterized by:

$\begin{matrix}{{L = {\frac{c}{Q}\sqrt{\frac{EIA}{\rho}}}},} & (1)\end{matrix}$where ρ is the density of the injected fluid, Q is the flow rate of theinjected fluid, A is the cross sectional lumen area of the cathetertube, E is the elastic modulus of the catheter tube material from whichthe outer wall 13 and septum 15 are formed, I is the area moment ofinertia of the outer wall and septum material, and c is a constant ofproportionality.

From equation (1), it is seen that the stability length L of thecatheter tube 12 can be increased by increasing one or more of theparameters E, I, and A. The increased size of the distal portion 30 ofthe catheter tube 12 and the portions of the lumens 14 it defines (FIGS.1 and 2) serves to increase both the area moment of inertia I and thelumen area A, which in turn improves the stability length L, whichcorresponds to a more stable tip within the vessel during fluidinjection. This tip stability of the distal portion 30 of the cathetertube 12 is especially helpful during power injection of fluids into thevessel, where catheter fluid flow rate Q can exceed about 5 cc/second.Under such conditions, the ability to preserve tip stability and reduceor eliminate tip whipping is especially beneficial.

As discussed above, an increase in the size of the distal portion 30and/or other portions of the catheter tube 12 increases the area momentof inertia I and thus improves tip stability. Note that I is directlyrelated by the fourth power of the radius of the catheter tube. As such,a relatively small increase in the cross sectional size of the cathetertube can have a significant effect on I, which enhances distal tipstability. Further note that I can be beneficially improved byincreasing the thickness of the outer wall and/or septum of the cathetertube while not increasing the area A of the lumen(s) of the tube.

Also, the flexural stiffness, defined as the product of the parameters Eand I, is higher in the distal portion 30 relative that of the proximalportion 20, in one embodiment, in order to provide distal tip stabilityduring fluid infusion. This can be accomplished by increasing theelastic modulus and/or the area moment of inertia for the distal portionover that of the proximal portion in any one of the ways discussedherein, or in other ways contemplated by one skilled in the art.

Again as discussed above, an increase in the size of the distal portion30 and/or other portions of the catheter tube 12 increases the area A ofthe lumens 14 and thus improves tip stability. Note that in otherembodiments lumen area A can be desirably increased in other ways aswell, including: a thinning of the outer wall and septum while takingcare not to reduce the area moment of inertia A of the distal portion;increasing the lumen area while maintaining the outer diameter of thecatheter tube constant, etc.

Though it can be formed to a variety of lengths to suit different usesand applications, in one embodiment the proximal taper region 24 of theproximal portion 20 is about 4 cm in length, the remainder of theproximal portion is about 20 to about 25 cm, the distal taper region 34of the distal portion 30 is about 4 cm, and the remainder of the distalportion is about 35 cm. Of course, other lengths for the varioussegments described above can be employed.

Moreover, the lengths, cross sectional sizes of, and relative sizedifferences between the various segments can also vary from what isshown and described herein, as appreciated by one skilled in the art. Inthe present embodiment, the approximate diameter, wall thickness, andseptum thickness (in inches) for each of the cross section views shownin FIGS. 3A-3C are, respectively: 0.095, 0.011, 0.008 (FIG. 3A); 0.063,0.0070, 0.0055 (FIG. 3B); and 0.070, 0.0080, 0.0060 inch (FIG. 3C). Notethat these are but one possible example of size configurations for thecatheter tube 12. Indeed a variety of sizes, including various Frenchsizes, can be employed for the catheter tube. In one embodiment, forexample, the proximal catheter portion defines a size in the range of2-6 French while the distal portion defines a size in the range of 2.5-8French. It should be further appreciated that the number, size, andother configuration of the catheter lumens can vary from what is shownhere. For instance, principles of the present disclosure can be employedwith triple and quad lumen catheters. In addition, though the lumens 14shown in FIGS. 3A-3C are symmetrically arranged, in another embodimentthe lumens can be included in an offset configuration so as to provideone or more relatively larger lumens for power injection, if desired.

In this and various other embodiments described herein the catheter tube12 is extruded or otherwise formed from one or more of a variety ofsuitable materials, including thermoplastic polyurethanes sold under thetrademarks TECOFLEX (type 93AB30) and TECOTHANE (type 95A) of LubrizolAdvanced Materials, Inc., and CARBOTHANE (type 95A), the thermoplasticelastomer sold under the trademark PEBAX of Arkema, Inc., silicone,polyesters, polyethylene, etc. Other suitable materials may also beacceptably used, as appreciated by one skilled in the art.

Note that, though the distal portion of the catheters described here aretrimmable, it is desirable that the length of the distal portionremaining after trimming is at least as long as the unsupported stablelength L as determined by equation (1), above. In one embodiment, thislength is from about 3 to about 10 cm, though other stable lengths arepossible, per equation (1).

FIG. 4 shows the catheter tube 12 according to another embodiment,including as before the proximal portion 20 and the distal portion 30joined by a taper region 35. As shown, the distal portion 30 is flaredin size from that of the proximal portion 20, thus providing forenhanced tip stability during power injection or other fluid infusioninto the vessel. Note further that, whereas the catheter tube design ofFIG. 2 provides for distal trimming of the tube, the catheter tube ofFIG. 4 is both proximally and distally trimmable so as to adjust thetube length to the anatomy of the patient. Note that in one embodimentthe amount trimmed from the distal end 12B of the catheter tube 12 ofFIG. 4 should be such that the remaining portion of the flared distalportion 30 is sufficiently long to ensure distal tip stability duringfluid infusion, as suggested by equation (1).

FIGS. 5 and 6 give further possible examples of flared catheter tubes12, wherein the tube of FIG. 5 includes a relatively short proximalportion 20 and a relatively long distal portion 30 extending to thedistal tube end 12B. As shown, in this embodiment the entirety of thedistal portion 30 serves as the distal taper portion 34 such that thecross sectional size of the distal portion steadily increases toward thedistal end of the tube.

In FIG. 6, the taper region 35 extends along the entirety of the lengthof the catheter tube 12 such that the entire tube includes a taper. Assuch, both the proximal portion 20 and the distal portion 30 aretapered, or flared. As before, the tapering disclosed in FIGS. 5 and 6provides for a relatively small and flexible proximal portion suitablefor placement in smaller portions of the vessel relatively close to thecatheter insertion site, while also providing a stable distal portionthat reduced or eliminates distal tip whipping during power injection orother fluid infusion through the distal end of the catheter tube. Suchcatheter tubes as those described here in connection with FIGS. 5 and 6or in other embodiments herein can include one, two, or more lumens.Note further that the catheter tube embodiments shown in FIGS. 5 and 6and in various other embodiments herein are distally trimmable to suitthe vasculature of the patient.

With reference to FIGS. 2 and 3C, note that in one embodiment arelationship between the thickness of the outer wall 13 and the crosssectional radius in the distal portion 30 of the catheter tube 12 isestablished, wherein the outer wall thickness equals about 0.24multiplied by the outer radius of the catheter tube in the distalportion. So configured, the distal portion 30 offers enhanced distal tipstability during power injection. Put another way, for a single lumenpower injectable catheter tube the product of I and A (and hence tubestability) can be maximized where the outer wall thickness of thecatheter tube equals about 0.24 of the catheter tube radius in thedistal portion thereof. This relationship can be extrapolated formulti-lumen catheter tubes as well. This relationship can be alsoemployed in a catheter tube regardless of whether the distal portionthereof is flared as shown in FIGS. 2, 4, 5, 6, etc. In anotherembodiment, the outer wall thickness can equal the product of the outerradius of the catheter tube and a number within a range of from about0.2 to about 0.3.

It is further appreciated that other catheter factors can be adjusted tomaximize distal tip stability for the catheter tube 12, including thelength of the flared distal portion alone and as a function of overallcatheter tube length, the density of the catheter tube material, thedegree of flare of the distal portion with respect to non-flared tubeportions, the interaction of modulus, area moment of inertia, and lumenarea in the flared portion, etc.

FIG. 7 shows a single lumen the catheter tube 12 according to oneembodiment, wherein the distal portion 30 includes the distal taperportion 34 such that a flared outer diameter 13B is defined by the outerwall 13. An inner diameter 13A defined by the lumen 14 remainssubstantially constant through the distal portion 30. The resultingincrease in thickness of the outer wall provides stability for thedistal portion 30 during fluid infusion into the vessel, thus reducingor preventing undesired distal tip whipping.

FIG. 8 shows that, in one embodiment, the proximal portion 20 and thedistal portion 30 of the catheter tube 12 can be configured so as toexhibit differing levels of the stiffness, or elastic modulus, E (seeequation (1)). For instance, in the present embodiment the proximalportion 20 includes a relatively soft material while the distal portion30 includes a relatively stiffer material so as to provide extrastrength at the distal end in order to increase the elastic modulus E ofthe distal portion, in turn reducing or preventing distal tip whipping.In yet another embodiment, the proximal and distal portions can exhibitsimilar stiffness at room temperature, but exhibit differing stiffnessafter implantation and subjection to internal body temperatures.

In one embodiment, both the proximal and distal portions are formed of asimilar material, with the distal portion being treated to be stifferrelative the proximal portion. Examples of such treatment of the distalportion include irradiation, application of a solvent or activator, heattreatment, etc. In another embodiment, it is the proximal portion thatis treated to exhibit a less-stiff elastic modulus.

In one possible embodiment, the entire length of the catheter tube canbe treated so as to exhibit a relatively stiff modulus. In anotherembodiment, the catheter tube can be extruded from two differentmaterials to provide a soft proximal portion and a relatively stifferdistal portion. In yet another embodiment, a soft proximal tube portioncan be formed then joined via adhesion to a pre-formed, relativelystiffer distal portion. These and other variations are thereforecontemplated.

FIG. 9 shows details of the catheter tube 12 according to anotherembodiment, wherein the distal portion 30 of the tube outer wall 13defines a plurality of flared segments 40 that each include an annularmaximum diameter point 42. The catheter tube 12 here is a dual lumentube with the lumens 14 separated by the septum 15. The plurality offlared segments gives the catheter tube 12 a knurled appearance. Theannular flared segments 40 are configured such that any one of thesegments can be cut at about the respective maximum diameter point 42,thus shortening the catheter length and providing relatively large andstable distal end fluid outlets for the lumens 14. Again, because of itsflared configuration for each of the catheter tube lumens 14, the distalportion 30 of the catheter tube 12 exhibits relatively larger values forboth the areal size A of the lumens and the area moment of inertia I.The number, size, and placement of the flared segments can varyaccording to application or catheter configuration.

FIG. 10 shows details of the catheter tube 12 according to anotherembodiment, wherein the tube defines first and second lumens 14A and 14Bseparated by the septum 15. As shown, the outer wall 13 of the cathetertube 12 remains cylindrical while the septum 15 in the distal portion 30includes a plurality of wave formations 46 that together define anundulating pattern. The distal portion 30 of the catheter tube 12 hereis trimmable such that the lumen size configuration at the trimmeddistal tip can be specifically selected. This shown in FIGS. 11A and11B, wherein if the catheter tube 12 is trimmed at the locationindicated at 11A-11A in FIG. 10, the lumen 14A will be larger in arearelative to the lumen 14B at the distal tip of the tube (FIG. 11A).

In contrast, trimming the catheter tube 12 at the location indicated at11B-11B in FIG. 10 will result in the distal tip lumen configurationshown in FIG. 11B, wherein the lumen 14B is larger in area relative tothe lumen 14A. In this way, a particular lumen 14 of the catheter tube12 can be selected to have a relatively larger distal tip opening inorder to stabilize the distal portion 30 within the vessel when fluid isinfused into the vessel from that lumen. Thus, it is seen that theundulating septum causes the cross sectional sizes of the lumens 14A and14B to vary inversely with respect to one another as a function oflength along the catheter tube 12. Of course, the catheter tube here canalso be employed without first being trimmed.

FIG. 12 shows another distal tip trimming configuration for the cathetertube of FIG. 10, wherein the tube is trimmed to define a staggereddistal tip. Specifically, the distal tip is trimmed with respect to theseptum wave formations 46 such that the areal size of the tip opening42A and 42B for each lumen 14A and 14B, respectively, is maximized. Thisresults in enhanced stability of the distal portion of the catheter tube12 within the patient's vessel during fluid infusion due to the increasein lumen area A at the catheter tube distal tip. Of course, otherstaggered tip configurations can be employed.

FIG. 13 shows details of a dual lumen catheter tube 12 according toanother embodiment, wherein the dual lumens 14 of the tube are separatedby the septum 15. At a predetermined distance L from the distal end 12Bof the catheter tube 12, a slit 50 is defined in the septum 15 such thatfluid communication is established between the lumens 14. So configured,the slit 50 enables the passage of fluid from one lumen 14 to the otherlumen during fluid infusion into the vessel of the patient in which thecatheter tube 12 is disposed. This in turn lowers the fluid pressure inthe lumen 14 from which fluid is passing through the slit 50 andincreases usable lumen area through which the fluid may pass from thecatheter tube 12 into the vessel. These effects contribute to increasetip stability and to prevent distal tip whipping within the vessel. Notethat the size, shape, number, positioning, and other variations of theslit can change according to other embodiments.

FIGS. 14A and 14B show details of the catheter tube 12 according toanother embodiment, wherein a proximal portion of the catheter tubeouter wall 13 includes a non-swellable first material 60. The distalportion 30 of the outer wall 13 includes a second material 70 that isconfigured to define a similar form factor to the proximal portions ofthe catheter tube including the first material 60 before insertion intothe patient's body. In contrast to the first material 60, however, thesecond material 70 is configured to swell to a larger size whensubjected to body heat or moisture after insertion into the vasculatureof the patient.

So configured, the distal portion 30 of the catheter tube 12 initiallydefines a similar outer diameter as that of the more proximal tubeportion (FIG. 14A), thus facilitating relative ease in inserting thecatheter tube into the patient vasculature. After placement is complete,the second material 70 of the distal portion 30 swells (FIG. 14B) to alarger inner diameter 13A and outer diameter 13B relative to the moreproximal catheter tube portion so as to provide a larger lumen area andouter wall thickness, which cooperate to increase distal tip stability.One example of a swellable material for use as the second material 70 isa biomaterial including polyurethane and polyethylene oxide sold underthe trademark AQUAVENE of Pierre Fabre Dermo-Cosmetique. Other swellingmaterials, such as suitable hydratable and hydrophilic materials canalso be employed. Use of a swelling material therefore serves as anotherexample, in addition to the other embodiments described herein, forproviding a catheter tube with a stable distal portion.

FIGS. 15 and 16 depict other configurations for use of the swellablematerial 70 described above in connection with FIGS. 14A and 14B. Inparticular, FIG. 15 shows inclusion of the swellable second material 70in the catheter tube 12 to define only an external tubular portion ofthe distal portion 30 of the catheter tube 12. The internal tubularportion of the distal portion 30, as well as the more proximal portionsof the catheter tube 12, is defined by the non-swelling first material60.

In FIG. 16, the swellable second material 70 extends proximally beyondthe distal portion 30 into more proximal portions of the catheter tube12 to define at least a portion of the outer surface of the cathetertube. A catheter tube manufactured in this fashion can be designed so asto vary in a predetermined and controlled manner the degree of swellingof the catheter tube along the length thereof after insertion into thepatient by controlling the amount of swellable material included in theouter wall along the tube length. It is noted that where a hydrophilicmaterial is included in the swellable material and defines the cathetertube in a manner similar to that shown in FIG. 16, the hydrophilicmaterial can improve the biocompatibility of the catheter tube incertain circumstances. Further note that the embodiments of FIGS. 15 and16 isolate the swellable material 70 from direct contact with fluidspassing through the lumen of the catheter tube for infusion into thepatient, thus preventing unintended absorption of the fluids by theswellable material. It is appreciated that the above catheter tubeconfigurations can be formed via extrusion or other suitable method.Also note that these configurations are just examples of many possiblecatheter tube designs including swellable and non-swellable materials.

Note that though the distal portions of the catheter tubes describedabove include both increased outer wall thickness and increased lumenarea relative to the more proximal portions of the catheter tubes, inother embodiments the outer wall thickness can vary independently oflumen area in the distal portion, and vice versa. Further, the lengthand relative size of the distal, proximal, and portions of the cathetertube can also vary from what is shown and described herein. Note alsothat various single and dual lumen catheters are described herein, butother multi-lumen catheters and tubular indwelling medical devices canalso benefit from the teachings herein.

FIGS. 17-19 show details of the catheter tube 12 according to possibleembodiments, wherein the catheter tube includes a multi-durometerconfiguration. In particular, FIG. 17 shows the catheter tube 12 formedby the outer wall 13, a proximal portion of which includes a relativelyhard (high durometer) first material 80. The first material 80 extendsdistally to the distal end 12B of the catheter tube 12 to define aninner diameter in the distal portion 30 of the tube. A second material90 that is softer (low durometer) relative the first material 80 isincluded atop the first material in the distal portion 30 to define anouter diameter surface of the distal portion. Such a multi-durometerconstruction can be achieved via a selective extrusion/coextrusionprocess, extrusion of the first material 80 followed by coating or otherapplication of the second material 90, etc. These and othermanufacturing methods are contemplated for this and the otherembodiments depicted in the succeeding figures.

The design of the catheter tube 12 as shown in FIG. 17 enables thedistal portion 30, which is inserted into the patient's vasculature, tobe relatively soft so as to enable the catheter tube to bend and bereadily positioned within a vessel without causing trauma to the vessel.In contrast, the more proximal portion of the catheter tube 12 formedfrom the first material 80 remains external to the patient in thepresent embodiment and is relatively harder with respect the secondmaterial 90 so as to enable it to withstand the relatively higher fluidpressures present in the proximal portion of the catheter tube whenfluid is infused therethrough.

FIG. 18 shows another possible catheter tube embodiment, wherein thedistal portion of the catheter tube 12 is formed exclusively from therelatively soft second material 90. The second material 90 also extendsproximally from the distal portion 30 of the catheter tube 12 to definean inner diameter of the more proximal portions of the tube, while therelatively harder first material 80 extends proximally from the distalportion 30 to define an outer surface of the catheter tube, as shown.Such a configuration increases the softness and flexibility of thecatheter tube 12 along its entire length, with substantial softnessalong its distal portion 30.

In FIG. 19, another possible catheter tube embodiment is shown, whereinthe distal portion of the catheter tube 12 is again formed exclusivelyfrom the relatively soft second material 90. The second material 90 alsoextends proximally from the distal portion 30 of the catheter tube 12 todefine an outer surface of the more proximal portion of the tube, whilethe relatively harder first material 80 extends proximally from thedistal portion 30 to define an inner diameter of the catheter tube, asshown. As with the previous two embodiments, such a configurationincreases the softness and flexibility of the catheter tube 12 along itsentire length, with substantial softness along its distal portion 30.

FIGS. 20 and 21 show that, in other embodiments, the multi-durometercatheter tube can also vary in diameter. For instance, FIG. 20 shows thedistal portion 30 of the catheter tube 12 as including an outer portionof the outer wall 13 formed by the second material 90 and the innerdiameter 13A defined by the first material 80. The first material 80extends proximally from the distal portion 30 to define the moreproximal portion of the tube outer wall 13, thus defining the uniformlysized inner diameter 13A along the entire length of the catheter tube12. The more proximal portion of the catheter tube 12 defined by thefirst material 80 is also sized to a larger diameter than the distalportion 30. FIG. 21 shows a similar configuration as that of FIG. 20,with the first material 80 defining a varying inner diameter for thecatheter tube 12. Thus, these embodiments illustrate the many variationspossible with multi-durometer catheter tube combinations. It should beappreciated that various other configurations are possible, includingreverse configurations of those illustrated and described herein.Non-limiting examples of materials that may be employed include thethermoplastics mentioned further above including an 80-95 A durometerrange for the second material 90, and a 95 A-60 D durometer range forthe first material 80.

FIG. 22 shows another multi-durometer catheter tube 12 according to oneembodiment, including the outer wall 13 defined by both the relativelyhard first material 80 and the relatively soft second material 90. Asshown, the proximal end 12A of the catheter tube 12 is definedcompletely by the first material 80, which tapers down gradually in thedistal direction so as to define an increasingly smaller portion of theouter wall 13 (and septum, if present). Correspondingly, the secondmaterial 90 defines a small portion of the catheter tube 12 proximatethe proximal end 12A and tapers up gradually in the distal direction soas to define an increasingly greater portion of the outer wall 13 (andseptum, if present) until at the distal end 12B the entirety of thecatheter tube is defined entirely by the second material 90. Thisvarying definition of the catheter tube outer wall can be seen in thecross sectional views of FIGS. 23A-23C, which are views at thecorresponding indicated locations along the catheter tube shown in FIG.22. Thus, each point along the length of the catheter tube 12 include aunique proportion of contribution to the outer wall composition by thefirst material 80 and the second material 90. Such a catheter tube asshown at 12 here can be manufactured using a co-extrusion or othersuitable process.

Definition of the catheter tube 12 in the manner shown in FIG. 22enables the distal portion of the tube to be substantially softerrelative more proximal portions of the tube, which is useful forproviding less traumatic insertion of the tube into the vessel of thepatient while still providing a relatively hard proximal portion forwithstanding the relatively greater pressures present in the proximaltube portion during power injection or other fluid infusion procedures.It is appreciated that variations to this design can be employed,including the contribution to the outer wall composition being varied ina step-wise fashion as opposed to the continuous fashion shown in FIG.22, reversal of the first and second materials, etc.

FIG. 24 gives various details of another configuration of the cathetertube 12 according to one embodiment, wherein the tube is dual lumen andthe distal portion 30 is flared to define a diameter greater relative tothat of the proximal portion 20. The tube 12 in the distal portion 30includes two single lumen tube structures, each defining one of thelumens 14, which are joined via a crease 94 therebetween, best seen inFIG. 25. This configuration offers the same benefits of a flared distalportion as in previous embodiments, e.g., reduction in distal tipwhipping within the vessel.

FIGS. 26 and 27 show that the outer wall 13 that defines the distalportion 30 of the catheter tube 12 can be folded or compressed in orderto substantially match in diameter the diameter of the proximal portion20. This enables the catheter tube 12 to be fed through an introducerand into the patient vessel. After placement of the catheter tube 12within the vessel is complete, the distal portion can unfold to its fullsize shown in FIG. 25.

For instance, FIG. 26 shows that the outer wall 13 defining the distalportion 30 of the catheter tube 12 can be compressed so as to close thelumens 14 and define a substantially closed, longitudinally extendingcavity 96. The cavity 96 is suitable in one embodiment for receivingtherethrough a guidewire for guiding the catheter tube into the vessel.A dissolvable adhesive or other suitable substance can be applied to thecatheter tube outer wall 13 so as to maintain the tube in the compressedstate until placement within the patient's vasculature is complete. Theadhesive can then dissolve, enabling the distal portion 30 of thecatheter tube 12 to expand to its fully open state.

FIG. 27 shows the outer wall 13 in a rolled configuration that enablesthe distal portion 30 of the catheter tube 12 to assume a diametersubstantially similar to that of the proximal portion 20 so as to easecatheter tube insertion into the patient's vasculature. Again, adissolvable adhesive or other suitable substance can be employed tomaintain the distal portion outer wall 13 in the rolled configurationduring insertion. In addition to the configurations shown in FIGS. 26and 27, other compression configurations are also possible. Also,catheter tubes defining more or fewer than two lumens can also benefitfrom the principles described herein. In the illustrated and otherembodiments described herein, it is further appreciated that the crosssectional geometry can also vary from proximal to distal ends, such asfrom round to oval, in one non-limiting example.

FIGS. 28A and 28B depict yet another stable configuration for the distalportion 30 of the catheter tube 12, wherein a plurality oflongitudinally extending stiffening ribs 98 are disposed on the outerwall 13. The ribs 98 serve to increase the area moment of inertia I forthe catheter tube distal portion 30, thus increasing tube stabilityduring fluid infusion therethrough and reducing or preventing distal tipwhipping. Though three ribs are shown disposed about the circumferenceof the catheter tube 12, more or fewer than this can be employed. Also,the size, shape, length, and placement of the ribs can vary from what isshown in FIGS. 28A and 28B. In one embodiment, the ribs can be disposedon an inner lumen surface of the distal portion.

In addition to the catheter tubes described herein as part of catheterassemblies, the principles disclosed can be employed with other tubularmedical devices as well.

Reference is now made to FIG. 29, which depicts various details of anaccess port assembly 110 according to one embodiment, including animplantable vascular access port (“access port”) 112 and a cathetertube, such as the catheter tube 12, operably connected to the accessport.

In greater detail, the access port 112 includes a body that defines areservoir 116 to which is access is provided via a needle-penetrableseptum 114 covering an opening to the reservoir. A stem 118 provides anoutlet to the reservoir 116 and is configured to operably connect withthe catheter tube 12 via a locking component 120. In one embodiment, thelocking component 120 includes a Cath-Lock-type catheter lockingcomponent available from Bard Access Systems, Salt Lake City, Utah. Inthe present embodiment, the access port 112 (and the catheter tube 12)is configured for power injection of fluids therethrough, where thefluid flow rate is about 5 cc or more per second. In other embodiments,the access port and/or catheter tube need not be power injectable.

As shown in FIG. 29, the catheter tube 12 is configured similar to thatshown in FIG. 2-3C, including the lumen 14 extending between theproximal end 12A and the distal end 12B of the catheter tube anddefining the proximal portion 20 and the distal portion 30. As before,the proximal taper region 24 is disposed adjacent the catheter tubeproximal end 12A and provides a transition in cross sectional area ofthe lumen 14 from a predetermined cross sectional lumen area at thecatheter tube proximal end 12A to a relatively smaller cross-sectionallumen area distal to the proximal taper region 24 of the proximalportion 20, as shown in FIGS. 31A and 31B, which cross sectionallydepict the outer wall 13 of the catheter tube 12 and the lumen 14 itbounds at the indicated points (in FIG. 29) along the longitudinallength of the catheter tube. Note that the catheter tube 12 defines atleast one lumen; as such, the catheter tube can include a single lumenas in the present embodiment, or more lumens as may be needed.

Note that an inner diameter of the stem 118 of the access port 112 inthe present embodiment is larger relative to other access ports ofsimilar size so as to match the relatively large cross sectional area ofthe lumen 14 in the proximal taper region 24 of the catheter tube 12when the stem and catheter tube are operably attached in a fluid-tightconfiguration. So configured, a relatively higher fluid flow ratethrough the stem 118 and catheter tube 12 is possible. As seen in FIG.30, this proximal taper region 24 of the catheter tube 12 is nottypically disposed in the vein, but rather resides outside thereof;thus, the relatively larger size of the stem 118 and the proximal taperregion does not impact occlusion of the vein in which more distal partsof the catheter tube are disposed.

Similarly, the distal portion 30 includes the distal taper region 34,disposed at the proximal end of the distal portion adjacent to thedistal end of the proximal portion 20, which provides a transition incross sectional area of the lumen 14 from a predeterminedcross-sectional lumen area proximal to the distal taper region 34 to arelatively larger cross-sectional lumen area distal to the distal taperregion and extending to the catheter tube distal end 12B, as shown inFIGS. 31B and 31C. Note that, though the cross sectional lumen area ofthe distal portion 30 in the present embodiment remains constant distalto the distal taper region 34, in other embodiments the cross sectionalarea of the distal portion could increase continuously (or in some otherfashion) toward the distal end 12B of the catheter tube 12.

The particular function and aspects of the catheter tube 12 of FIG. 29as described here are similar to those discussed further above inconnection with FIGS. 1-3C. In the illustrated embodiment, thenon-tapered segment of the proximal portion 20 of the catheter tube 12is sized as a 5 French catheter portion while the non-tapered segment ofthe distal portion 30 is sized as a 6 French catheter portion. In yetanother embodiment, the non-tapered segment of the proximal portion 20of the catheter tube 12 is sized as a 4 French catheter portion. In yetanother embodiment, the non-tapered segment of the distal portion 30 ofthe catheter tube 12 is sized as an 8 French catheter portion. Thisnotwithstanding, other sizes and relative size differences between theproximal and distal catheter tube portions, both smaller and larger, arealso possible.

Reference is now also made to FIG. 30, which depicts disposal of theaccess port assembly 110 within a patient 130, according to oneembodiment. As shown, the access port 112 is disposed in a subcutaneouspocket defined in an upper arm portion of the patient 130, though manyother placement locations, including other limbs, are possible for theaccess port. The proximal end 12A of the catheter tube 12 is operablyattached to the stem 118 of the access port 112, and that catheter tubeextends into a vasculature 132 of the patient via an incision 133defined in a vessel proximate the subcutaneous pocket in which theaccess port 112 is disposed. Note that placement of the access port 112in an arm of the patient is often preferred so as to better obscure thepresence of the port and to avoid the creation of a scar on thepatient's chest, as occurs when the port is placed in the chest of thepatient. Note, however, that the principles to be described below applyto access port assembly placement in the arm, chest, and other bodylocations.

As shown, the catheter tube 12 extends from the access port 112 andenters a vessel of the patient vasculature 132, such as a basilic vein134 as depicted in FIG. 30, and extends distally through an axillaryvein 136, in the present embodiment. So positioned, the relativelysmaller proximal portion 20 of the catheter tube 12 is primarilydisposed within the basilic and axillary veins 134, 136, which arerelatively small veins, in terms of cross sectional area, given theirdistance from a heart 140 of the patient 130.

The catheter tube 12 further extends within the patient vasculature 132such that the distal portion 30 thereof is disposed within a relativelylarge vein, such as a subclavian vein 138 in the present embodiment. Thedistal end 12B of the catheter tube 12 terminates at a desired location,such as proximate a superior vena cava (“SVC”) 142 of the heart 140 inthe present embodiment, as shown in FIG. 30. So positioned, therelatively larger distal portion 30 of the catheter tube 12 is primarilydisposed within the subclavian vein 138, which is a relatively largevein in terms of cross sectional area, given its relatively shortdistance from the heart 140.

In light of the above, it is seen that the relatively small proximalportion 20 of the catheter tube 12 is disposed within the relativelysmall basilic and axillary veins 134, 136, while the relatively largerdistal portion 30 of the catheter tube is disposed within the relativelylarger subclavian vein 138. As has been described further above inconnection with previous embodiments, this provides several benefits.For one, it helps prevent undesired catheter tube-caused occlusion ofthe vein by matching the cross-sectional size of the portion of thecatheter tube 12 with a corresponding relative cross-sectional size ofthe vein in which the catheter tube portion is disposed. Also, itassists in reducing the risk of thrombus and intimal damage within thevein. Further, the relatively smaller size of the catheter proximalportion 20 enables it to bend more easily during insertion into thepatient's vasculature along a potentially tortuous path, resulting inless trauma and damage to the vessel.

Additionally, the relatively larger size of the distal portion 30 of thecatheter tube 12 helps to provide stability to the distal end 12B of thecatheter tube when fluids are power injected therethrough, thus helpingto prevent whipping of the catheter tube distal end against vesselwalls. Because of the relatively larger sizes of the lumen(s) 14 in theproximal taper region 24 and the distal portion 30, fluid flowresistance through the catheter tube 12 is reduced, which is beneficialespecially during power injection of contrast media through the cathetertube. In one embodiment, power injection through the catheter tube 12can exceed typical rates of about 5 cc/second given the relative generalincrease in catheter tube lumen size, all while preserving a relativelysmall size for the portion of the catheter tube that resides withinrelatively small veins, as shown in FIG. 30. Reference is made toBernoulli's fluid flow principles and general thrust principles, whichteach that fluid exiting the distal end 12B of the catheter tube 12described in connection with FIGS. 29-31C will slow in velocity as itexits and will reduce the thrust force on the catheter tube itself, thushelping to prevent whipping of the distal catheter tube end.

Embodiments of the invention may be embodied in other specific formswithout departing from the spirit of the present disclosure. Thedescribed embodiments are to be considered in all respects only asillustrative, not restrictive. The scope of the embodiments is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A method of manufacturing an implantable vascularaccess port system, the method comprising: producing an implantablevascular access port; and forming a catheter designed for coupling tothe implantable vascular access port, the catheter comprising: at leastone lumen extending from a proximal end to a distal end; a proximalportion including a first cross sectional lumen area; a distal portionincluding a second cross sectional lumen area larger than the firstcross sectional lumen area, the distal portion designed to preventwhipping when the catheter is disposed in a patient and a fluid exitsthe at least one lumen; and a taper region interposed between theproximal portion and the distal portion, the taper region having a crosssectional lumen area transitioning from the first cross sectional lumenarea to the second cross sectional lumen area.
 2. The method ofmanufacturing according to claim 1, wherein the forming step comprisesextruding the catheter from a thermoplastic polyurethane material. 3.The method of manufacturing according to claim 1, wherein the formingstep comprises forming the distal portion of the catheter to have anarea moment of inertia greater than an area moment of inertia of theproximal portion of the catheter.
 4. The method of manufacturingaccording to claim 3, wherein the forming step comprises forming atleast part of the distal portion of the catheter to have an arithmeticproduct of an elastic modulus greater than an arithmetic product of anelastic modulus of at least part of the proximal portion of thecatheter.
 5. The method of manufacturing according to claim 1, whereinthe forming step comprises forming the proximal portion of the catheterto include a proximal taper region transitioning from a third crosssectional lumen area at the proximal end of the catheter to the firstcross sectional lumen area, the third cross sectional lumen area greaterthan the first cross sectional lumen area.
 6. The method ofmanufacturing according to claim 1, wherein the producing step comprisesmaking the implantable vascular access port for placement in a limb ofthe patient.
 7. The method of manufacturing according to claim 6,wherein the producing step comprises making the implantable vascularaccess port for placement in an arm of the patient.
 8. The method ofmanufacturing according to claim 7, wherein the forming step comprisesforming the proximal portion of the catheter for placement in a vein inthe arm of the patient.
 9. The method of manufacturing according toclaim 8, wherein the forming step comprises forming the proximal portionof the catheter for placement in at least one of a basilic vein and anaxillary vein, and forming the distal portion of the catheter forplacement in a subclavian vein.
 10. The method of manufacturingaccording to claim 1, wherein the producing step comprises includingpower injectable features in the implantable vascular access port foruse as a power injectable access port.